Abstract:
The influence of fire regimes on soil microbial diversity in montane grasslands is a relatively
unexplored area of interest. Understanding the belowground diversity is a crucial stepping-stone
toward unravelling community dynamics, nutrient sequestration, and overall ecosystem stability. In
this study, metabarcoding was used to unravel the impact of fire disturbance regimes on bacterial
and arbuscular mycorrhizal fungal community structures in South African montane grasslands that
have been subjected to an intermediate (up to five years) term experimental fire-return interval
gradient. Bacterial communities in this study exhibited a shift in composition in soils subjected to
annual and biennial fires compared to the controls, with carbon and nitrogen identified as significant
potential chemical drivers of bacterial communities. Shifts in relative abundances of dominant
fungal operational taxonomic units were noted, with Glomeromycota as the dominant arbuscular
mycorrhiza observed across the fire-return gradient. A reduction in mycorrhizal root colonisation was
also observed in frequently burnt autumnal grassland plots in this study. Furthermore, evidence of
significant mutualistic interactions between bacteria and fungi that may act as drivers of the observed
community structure were detected. Through this pilot study, we can show that fire regime strongly
impacts bacterial and fungal communities in southern African montane grasslands, and that changes
to their usually resilient structure are mediated by seasonal burn patterns, chemical drivers, and
mutualistic interactions between these two groups.
Description:
DATA AVAILABILITY STATEMENT : The data presented in this study are openly available in the Sequence
Reads Archive (SRA) database of the National Centre of Biotechnology Information (NCBI) under
BioProject accession number PRJNA422406 (SRP126751).
SUPPLEMENTARY MATERIALS : FIGURE S1: Mycorrhizal colonisation structures visualized by light microscopy (1: vesicle, 2: intercellular hyphae, 3: arbuscule); FIGURE S2: Distance-based RDA ordination of fungal data. Vectors indicate the direction of the soil chemistry parameter effect in the ordination plot; TABLE S1: Diversity indices generated for bacteria and AM fungi on Roche and MiSeq platforms; TABLE S2: Statistical analysis at phylum level for the soil bacterial community in burn-treated soils where statistical significance is indicated by p 0.05; TABLE S3: BLAST analysis of select dominant fungal OTUs against the NCBI nucleotide database from which the uncultured/environmental sequences were omitted; TABLE S4: Marginal and sequential tests from distance-based redundancy analysis of the bacterial community; TABLE S5: Marginal and sequential tests from distance-based redundancy analysis of the fungal community.
